Drill



1,516,61 A; L. HAWKESWORTH DRILL Original Filed July '7, 1922 Patented Nov. 25, 1924.

units ears were PTNT ew enrnun LEE newnnsw'on'rn, or. Barres/rename, essrsnon 'ro nswnnswonrn DRILL COMPANY, or BUTTE, .Mon'mnn A CORPORATION or DELAWARE.

DRILL.

' Original applicatign f led y 7, 1922, Serial No. 573,288. Divided and this application filed February 7,.

To all whom z'tmay concern: Be it known that I, ARTHUR LEE HAwnEs won'rH, a citizen of the United States, residing at Butte, in the county of Silver Bow and State of Montana, have inyented certain new and useful Improvements in'lDrills, of which the following is a specification.

My invention has relation to improve ments in drills having detachable bits which maybe quickly and readily detached when occasion arises therefor, for example,'where a bit mustbe removed for sharpening and a -new bit-substituted, or when it is desired to takethe bit off for, safekeeping, or for any other purpose. A further object. is to provide a drill having a detachable bit'with sides inclining upwardly to a single cutting edge, the joint between bit and shank being so formed as to preserve the maximum strength thereof. Further objects will be I better apparent from a detailed description of the invention in connection with the ac-" p drilhng operations will, tend to tighten the companying drawings, in which, Figure 1 is a side elevation of my improved drill turned to show theinterlocking grooves and tongues in end elevation; Fig. 2-is a side elevation of the drill turned to an .angle of 90 to Fig. 1; Fig. 3 is an elevation of the bit detached from the shank 0 turned to present the narrow end of the central tongue; Fig. 4 is an elevation of the shank turned to present the narrow end ofits central groove adapted toreceive the tongueof the bit; Fig. 5. is a plan view of as thetongue andfgrooy'e formations on the shank. Referring to-the drawings, 1 represents a drill-bar or shank andv 20 the bit adapted to be-passed-across the axis thereof, said shank no and bit having cooperative formations whereby they are effectively interlocked against relative displacement, the bit, atthe same time, being readily detachable from the shank" These interlocking formations consist in a dovetail groove 24:- in the shank bounded by inwardly inclined tongues 25, 25 which cooperate with a dovetail tongue 23 on the bit bounded by inwardly inclined ooves 26, 26, all of said formations being' .50 inclined to the axis of the drill.

We ls of the. tongues 25, 25 taper the gen- The side eral direction toward the cutting end of the drilltwhile the side walls of groove 24:.taper 1n theopposlte direction so that on inserting the narrow endof tongue 23 into the wide lock until further movement of the bit/is arrested, whenv the axis of shank and bit are in alinement', and the bottom of the grooves and outer surfaces 'of the tongues (the transverse'engaging surfaces) are in engagement.

This arrest is effected by the wedging action between tongue 23 and groovei'24 on the one hand, and the tongues 25, 25 and grooves 26, 26 on the other hand, the reverse tapers of the respective tongues'and their cooper ating grooves operating to efi'ect a positive locking of the bit tothe shank. 'Obviously,

the blows to which the drill is subjected in hammer against the bit on the same side with the narrow end of tongue 23.

In the present case the drill is provided with a bit 20 having but a single. cutting edge 21, the opposite sides 22, 22 of the bit this edge, thus decreasing the width of the bit across the interlocking formations. While the central tongue 23 ofthe bit and its cooperating groove 24: in the shankare dovetailed, the 'tongues 25, 25 of the shank and cooperating grooves 26, 26 of the bit being inclined toward each other to form this plane intersects the surfaces of, each .tongue 25 will be parallel. This inclination of walls 'w, w ives increased thickness to the outer bounding shoulders 27, 27 of the.

bit.

From the foregoing it is apparent that with the Walls w, w inclined inwardly there is less possibility of a line of fracture developing under the strain of the Work across the bases of shoulders 27, 27.

The herein described improvements may alsobe embodied with advantages in a drill of the construction of that shown in my copending case, Serial No. 573,288, of which this is a division.

Having described my invention, I claim: 1. In combination With a drill bar or shank, a bit movable across the axis of the shank, a transverse dovetail tongue tapering in a given direction and bounding grooves tapering in the opposite direction formed on one of the members, bounding lines of the side Walls of'each groove lying in a common plane intersecting said grooves being substantially parallel, a corresponding dovetail groove and bounding tongues on the op' posite member interlocking with the formations on the first member, the transverse engaging surfaces between the members being inclined to the axis of the shank.

. 2. In combination with shank, a bit movable across the axis of the shank, a transverse dovetail tongue tapera drill bar or ing in a given direction and bounding,

grooves tapering in the opposite direction formed on one of the members, a corresponding dovetail groove and bounding tongues on the opposite member interlocking with the formations on the first member, the outer engaging Walls of the bounding tongues and grooves inclining toward the axis of the bit, and the transverse engaging surfaces between the members inclining-to the axis of the shank;

3. In combination with a drill bar or shank, a movable across the axis of the shank, said bit having side Walls inclining upwardly toward'each other to form the cutting edge thereof, a transverse dovetail tongue tapering in a given direction and bounding grooves tapering in the opposite (lirectiOn formed on the bit, the shank having a corresponding dovetail groove and bounding tongues interlocking With the formations on the bit, the outer engaging walls of the bounding tongues and grooves inclining in the same general direction as the bit side Walls.

In testimony \vhereof I hereunto aflix my signature.

ARTHUR LEE HAWKESWORTH. 

